Electrical coloration recording sheet

ABSTRACT

A thin electrically conductive material layer is provided on an electrical coloration material layer of the sheet. Upon scanning the thin conductive material layer by a recording electrode, it is possible to produce a recorded likeness of the original on the sheet by information signals as the color image of the electrical coloration material is controlled by the signals.

United States Patent n91 Yasumori et a1.

June 24, 1975 ELECTRICAL COLORATION RECORDING SH EET Inventors: AkiyoshiYasumori; Katsuichi Ohta,

both of Yokohama} Makoto Kunikane, Tokyo; Michiharu Abe, Kawasaki, allof Japan Assignee: Ricoh Co., Ltd., Tokyo, Japan Filed: July 27, 1973Appl. No.: 383,160

Foreign Application Priority Data Aug. 8, 1972 Japan 47-79260 US. Cl204/2; 346/74 E; 346/76;

346/135 Int. Cl. 841m 5/20; GOld 15/34 Field of Search 204/2; 178/62;96/1 E;

346/74 CH, 74 E, 135, 76

[56] References Cited UNITED STATES PATENTS 2,554,017 5/1951 Dalton204/2 3,299,433 1/1967 Reis l 204/2 3.689,768 9/1972 Sato 346/1353,786,518 1/1974 Atherton 1 346/135 3,789,425 1/1974 Matsushima 346/135Primary Examiner- T. M. Tufariello Attorney, Agent, or Firm-Cooper,Dunham, Clark, Griffin & Moran [57] ABSTRACT 16 Claims, 2 DrawingFigures INFORMATION SIGNAL I PATENTEDJuu24 ms 3.891, 513

FIG. I PRIOR ART 'IIIIIIIIIIIIIIIIIIIIIIIIIIJ ELECTRICAL COLORATIONRECORDING SHEET BACKGROUND OF THE INVENTION This invention relates to anelectrical coloration recording sheet capable of electrically producinga recorded likeness of an original thereon.

in producing a recorded likeness of an original by, .g., a facsimilereceiver or an output device of a com puter, it is needed to use sheetsresponding to electricity which are easy to handle, high in the degreeof precision and low in running cost while permitting high speedproduction of a recorded likeness of the original to be carried out.

Heretofore, in the facsimile system, for example, it has been customaryto employ an electrolytic recording process, electrical dischargerecording process or an electrostatic recording process to produce afacsimile record of an original from electric signals. However, none ofthese processes meet the aforementioned requirements.

The electrolytic recording process employs a recording sheet produced byimpregnating paper or other like material with polyhydric phenol and ananode made of iron. A voltage is impressed on the recording sheet whilethe latter is in moist condition to produce a brown image byelectrolysis. This process has disadvantages. Since the recording sheetshould be wet in operation, difficulty is experienced in handling thesheet. The use of wet sheets often leads to corrosion of parts of theapparatus. Besides, the images formed on the sheets of this type leavemuch to be desired in tone, contrast, resolution and longevity.

In the sparking recording process, a white colored material layer formedby applying to a carbon layer of a supporter of a recording sheet atitanium oxide mixed with a resin supporter is subjected to a dischargeof high voltage so as to destroy portions of the white colored materiallayer and expose the underlying carbon layer, so that an image of theoriginal can be produced on the recording sheet. Some disadvantages areassociated with this process. The use of a current of high voltage makesit necessary to take special precaution in operation. The resin binderis burned when the white colored material layer is destroyed andproduces odor. Portions of the white colored material layer aredestroyed and adversely affect the apparatus. The recording sheet itselfis fragile and difficult to handle because it consists of many layers.The images formed on the recording sheets of this type lack harmony.

The electrostatic recording process is such that a voltage is impressedas by a contact electrode on a recording sheet comprising a dielectricmaterial layer formed on a supporter which may be paper or other likematerial treated to be electrically conductive so as to form on therecording sheet an electrostatic latent image which is developed into avisible image. The need to develop the latent image into a visible imageentails the use of a developing device which renders the process complexin steps and prolongs the time elapsing before the visible image isproduced. Moreover, the images formed by this process are not fullysatisfactory in quality.

Proposals have been made to use color developing recording sheets, suchas the one described in Japanese Patent Publication No. 2234l/63., whichdepends for their operation on the action of an electric current passedthereto. This type of recording sheets generally comprise a colorationmaterial layer 3 disposed on a conductive material layer 2 which isprovided on an insulating supporter l as shown in FIG. I. In recordingan information on this type of sheets, an electrode 5 connected to oneterminal of a power source 4 is maintained in contact with theconductive material layer, and a recording electrode 5 connected to theother terminal of the power source 4 is used to scan the colorationmaterial layer 3 so as to impress a voltage on the layer 3 whilecontrolling the passing of a current thereto by signals obtained from afixed graphic material.

As can be seen in FIG. 1, the voltage applied to the coloration materiallayer 3 is oriented perpendicularly to the longitudinal surface of thecoloration material layer 3. It is believed that the operation of thelayer 3 to color depends on a combination of effects including oxidationand reduction caused by the movement of electrons and ions made upon theimpression of voltage, the heating effect of a current or Joules heat,and the impact of thermionic emission of electrons on the colordeveloping material layer. It is necessary to reduce the resistanceoffered by the layer 3 in order to obtain an image of high quality. Thehigh resistance offered by the coloration material layer 3 to thepassing of a current would interfere with the mobility of ions andelectrons and the generation of Joules heat, thereby reducing thedensity of the color developed. When a stylus electrode is employed as arecording electrode, an image produced may be cut off in several partsand lack continuity due to high resistance.

The need to reduce the resistance of the coloration material layer hashitherto placed limits on the materials used as coloration agents andbinders. This has resulted in increased cost and a narrow range ofcolors to choose from.

SUMMARY OF THE INVENTION This invention obviates the aforementioneddisadvantages of the conventional recording sheets whose operationdepends on the action of a current passed thereto. Accordingly, theinvention has as its object the provision of a novel electricalcoloration recording sheet comprising an electrically conductivematerial layer of small thickness provided on a coloration materiallayer which is discolored or which colors upon impression of a voltagethereon.

1n the electrical coloration recording sheet according to the invention,the voltage applied thereto is not oriented perpendicularly to belongitudinal surface of the sheet as has hitherto been the case with asimilar type of conventional recording sheets, but is oriented along theplane of the longitudinal surface because the coloration material layerof the recording sheet is coated with a conductive material layer ofsmall thickness. The operation of the coloration recording sheetaccording to the invention depends primarily on the heating effectproduced by the resistance of the conductive material layer to therecording electrode brought into contact therewith and the impact ofthermionic emission of electrons from the recording electrode on thecoloration material layer. A reduction phenomenon caused to take placein the color developing material layer by the thermoelectrons breakingthrough the conductive material layer and impinging on the colorationmaterial may also be a contributing factor. It is intereiting to notethat the electrical coloration material layer is heated almost to itsmelting point by a relatively low voltage to which it is exposed.Portions of the conductive material layer are removed by melting orevaporation and perform a sort of catalytic action in coloring ordiscoloring the coloration material layer.

The most important feature of this invention is that any colorationmaterial may be used regardless of its resistance value, so that acomposition for forming the coloration material layer may be selectedfrom an almost infinite range of compositions. Thus, it is possible toselect and use any material which colors most satisfactorily and toselect any color that is to be developed. Besides, the use of theelectrical coloration sheet according to the invention offers theadditional advantage of permitting the electrode to be handled readilyin operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows aconventional recording sheet depending for its operation on the actionof a current and means used for recording information thereon; and

FIG. 2 schematically shows an electrical coloration recording sheetaccording to the invention and means used for recording informationthereon.

DESCRIPTION OF A PREFERRED EMBODIMENT The composition of the materialsused for producing an electrical coloration sheet according to theinvention and the production process thereof will now be described.

As shown in FIG. 2, the electrical coloration recording sheet comprisesa supporter ll, a coloration material layer 12 disposed on the supporter11 and a thin conductive material layer 13 disposed on the colorationmaterial layer 12.

Any material selected from the group consisting of a plastic in sheetform, glass in sheet form, cloth, paper, synthetic paper and tracingpaper, can be used as a supporter l 1.

The coloration material making up the layer 12 may be a mixture of acoloration material or materials selected from the materials of group(I) and a binder or binders selected from the materials of group (ll),and such mixture preferably comprise a coloration material or materialsand a binder or binders in a range of ratios by weight of 20 to l to lto 2. The mixture is kneaded as by a ball mill and applied as by a wirebar to the surface of the supporter 11 to form a layer ranging inthickness from 1 to 100p. It is to be understood that the colorationmaterial layer l2 may be formed by vacuum evaporation of a material ormaterials or group (I) alone on the supporter 11.

1. Electrical coloration material:

a. Samples of metal sulfides:

ZnS, Sb,S,, ln,S;,, and the like.

b. Samples of metal oxides:

Rb 0., Cs,0;,, ZnO, Cd,O HgO, GaO, Ga lnO, TiO,SnO,, Pb O 3, V 0 Nb,0Ta,0,,, Shop, sbgog, C110 CrO M003, W203, T60 Teoa, Mnog, R6207, RUG0S0, C0203, C030, and the like.

c. Samples of metallic acids:

HSbO HVO Hgseog, HgTiOa, Hzsnoa, H 860 HgMOO H WO HQUO4, Hasboa, H3Sb0H4110, HgMOOa, H Sb H TaO H5Sb05, HgTeos, H SnO Hgpbo H [SiMo O, 30 H O,

H [PMo, 0.,,,] 30 H O,

H [PW, 0 30 H 0, and the like.

d. Samples of salts of metallic acids:

The salts of the metallic acids described in (c), for

example:

K Mo0 Na Mo0 (NH4 )2M004,

( fiel v ul 4 2 e. Another metallic compounds:

CuSCN, PbSCN, and the like.

f. Therrnochemical coloration material:

Zinc stearate Diphenylcarbazol,

Iron stearate l-formyl-4-phenylsemicarbazido,

and the like.

Materials of this subgroup color by forming, e.g.,

chelate compounds by the heating effect of a current.

ll. Binders:

a. Samples of oil soluble resins:

Pliolite S -5B Styrene butadiene copolymer made by Goodyear Tire andRubber Co.

Pliolite S 7 Same to above.

Nylon resins Styrene-methyl methacrylate Butyl acrylate Acryl resinPolyvinyl pyrrolidone Polyvinyl acetate and the like.

b. Samples of water soluble resins:

Polyvinyl alcohol (P. V. Ac.) Made by Dow Chemical Co.

Conductive polymer 261 Made by Calgon Co.

and the like.

c. Another binders:

Gelatine, Starch paste, and the like.

The thin conductive material layer 13 provided on the colorationmaterial layer 12 may be formed by either vacuum evaporization orsputtering method on the layer 12 of a material or materials listedbelow or applying to its surface a mixture of a material or materialslisted below with a binder material or materials listed in group (ll)above. The surface resistance of the coloration material layer 13 is setat less than 10 (0), or preferably in a range from 10 to 10 (Q). (lll)Thin conductive material layer forming materials:

a. Metals:

Fe, Co, Ni, Al, Cu, Au, Ag, Zn, Ti, In, and the like.

b. Metallic compounds:

1n,o,, SnO Cul, CuBr CuBr, Pbo,, FeS,,

and the like.

In' recording an image of an original by using information signalsacting on electrical coloration recording sheet made from the variousmaterials listed above, an electrode 15 connected to one terminal of apower source 14 is brought into contact with one comer of the thinconductive material layer 13, and a recording electrode 16 connected tothe other terminal of the power source 14 is used to scan the thinconductive layer 13 so as to form an image from information on the sheetby controlling the passing of a current to the sheet by informationsignals.

CaMolL, PbMo0 More specifically, if a voltage is impressed on the thinconductive material layer 13 through the recording electrode 16 by aninformation signal, a current will flow in the thin conductive materiallayer 13 from the point of contact between the recording electrode l6and layer 13 to the electrode 15. The resistance offered by the point ofcontact on the layer 13 is what is referred to as a contact resistanceand a very high in value, so that the heat generated at the point ofcontact is sufficiently high to cause the corresponding portion of thecoloration material layer 12 to color. At the same time, thermoelectronsare produced by the recording electrode 16 and supplied to the thinconductive material layer 13, with some of them breaking through layer13 and invading layer 12 to cause reduction to take place on layer 12.Thus, portions of the conductive material layer 13 on which the voltageis impressed by contact with the recording electrode 16 are removed byeither melting or evaporation due to the heat generated therein andperform a sort of catalytic action in a thermal coloring reaction. Thus,a recorded likeness of the original is produced on the sheet by scanningthe surface of the thin conductive material layer 13 while controllingthe passing of the current from the fonner to the latter by informationsignals. The recorded image is very clear, well defined and high indensity.

Example 1 A mixture of parts of H,Mo0,. 2l-l,0, 2 parts of Pliolite S-7(trade name) and 30 parts of toluene (the parts are all by weight) wasplaced in a ball mill and kneaded for fifteen minutes. Then, the mixturewas applied by a wire bar to the surface of a sheet of commerciallyavailable tracing paper to form a layer thereof of about 5;]. inthickness, and dried for half an hour by exposing the layer to dry airof 100C.

An electrically conductive material layer was formed, on the electricalcoloration layer formed as aforementioned, by vacuum evaporation ofaluminum thereon under the pressure of l0' mmHg. The conductive materiallayer formed had a surface resistance of 10 0. The electrical colorationdeveloping recording sheet produced in this way was tested by scanningits surface with Toshafax made by Tokyo Aircraft Meters Company andpassing thereto an alternating current of about 100 volts to theconductive material layer. A clear black positive image of the originalwas produced.

Example 2 A mixture of 10 parts of ZnO, 2 parts of P.V.Ac. and 30 partsof methanol (the parts are all by weight) was placed in a ball mill andkneaded for four hours. Then, the mixture was applied by a wire bar tothe surface of a sheet of commercially available high quality paper toform a layer thereof of about lOp. in thickness, and dried for half anhour at 100C.

An electrically conductive material layer was formed, on the electricalcoloration material layer formed as aforementioned, by vacuumevaporation of aluminum thereon under the pressure of 10mml-lg. Theconductive material layer has a surface resistance of 10 .0. Theelectrical coloration recording sheet produced in this way was tested byscanning its surface with the Toshafax referred to in Example 1 andpassing thereto a direct current of about +75 volts. A dark brownpositive image of the original was produced.

Example 3 A mixture of 10 parts of V 0 3 parts of RP 505 (made byMonsanto Company), 5 parts of water and 25 parts of CH OH (the parts areall by weight) was placed in a ball mill and kneaded for 8 hours. Then,the mixture was applied by a wire bar to the surface of a sheet of acommercially available high quality paper to form a layer thereof ofabout 5p. in thickness, and dried for half an hour by exposing the layerto dry air of 100C.

An electrically conductive material layer was formed, on the electricalcoloration material layer formed as aforementioned, by vacuumevaporation of aluminum thereon under the pressure of l0"'mml-lg. Theconductive material layer formed had a surface resistance of 10 0. Theelectrical coloration recording sheet produced in this way was tested byscanning its surface with the aforementioned Toshafax and passingthereto a direct current of +1000 volts to the photoconductive materiallayer. A clear pure black positive image of the original was produced.

Example 4 A mixture (1) of 1 part of zinc stearate, 5 parts of P.V.Ac.and 20 parts of methanol (all the parts are by weight) and a mixture (2)of 1 part of diphenylcarbazone, 10 parts of P.V.Ac. and 20 parts ofmethanol (all the parts are by weight) were placed in separate ballmills and kneaded for 4 hours. Then, the mixtures (l) and (2) were mixedtogether and applied by a wire bar to the surface of a commerciallyavailable polyester film to form a layer thereof of about 10 pinthickness, and dried for half an hour at C.

An electrically conductive material layer was formed, on the electricalcoloration material layer formed as aforementioned, by vacuumevaporation of indium thereon under the pressure of 10'' mmHg. The thinconductive material layer thus formed had a surface resistance of 5 X 100. When it was tested by scanning its surface with the aforementionedToshafax and passing thereto a direct current of +500 volts, a beautifulpositive image was produced.

Example 5 A mixture of 5 parts of ZnO, 5 parts of ln,O 2 parts ofP.V.Ac. and 30 parts of CH -,Ol-l (all the parts are by weight) wasplaced in a ball mill and kneaded for 8 hours. Then, the mixture wasapplied by a wire bar to the surface of a sheet of commerciallyavailable tracing paper to form a layer thereof of Spin thickness, anddried for 50 minutes in dry air at l00C.

A transparent Cul film of several 0 was formed, on the surface of theelectrical coloration material layer thus formed, by vacuum evaporationof copper under the pressure of l0 mmHg and then by exposing thedeposited material to iodine in vapor form. The thin conductive materiallayer or Cul film formed in this way had a surface resistance of 10 0.Tests performed by scanning the surface of the electrical colorationrecording sheet with the aforementioned Toshafax and passing thereto adirect current of +300 volts showed that the sheet was capable ofproducing a dark brown clear positive image thereon.

Example 6 A mixture of 10 parts of (NH ),Mo O24.4H O 2 parts of crotonicacid acrylic acid ester copolymer and 30 parts of methanol was placed ina ball mill and kneaded for 10 hours. Then, the mixture was applied by awire bar to the surface of a sheet of commercially available tracingpaper to form a layer thereof of about 5 in thickness, and dried for 30minutes in dry air at 100C.

An electrically conductive material layer was formed, on the surface ofthe electrical coloration material layer formed in this way, by vacuumevaporation of indium under the pressure of l""mml-lg, so that theconductive material layer formed had a surface resistance of aboutlOOOfl. Tests conducted by scanning the surface of the electricalcoloration recording sheet to carry out recording of information showedthat a clear black positive image was produced.

Example 7 A electrically conductive material layer was formed on thesurface of the electrical coloration material layer formed by the sameway described in Example 6, by spattering method of SnO under thepressure of l0mmHg in 95% Argon- Oxygen mixed gas. The electricallyconductive material layer had a surface resistance of about 10 K0,.

As the result of the same tests as described in Example 6, a clear blackpositive image was produced.

What is claimed is:

1. An electrical coloration recording sheet comprising an electricalcoloration material layer and a thin electrically conductive materiallayer formed on said electrical coloration material layer, saidelectrical coloration material layer made of a material which changescolor but is not destroyed at a point adjacent a point of the thinelectrically conductive material layer to which a selected electricalsignal is applied with a re cording electrode whereby a recordedlikeness of an original may be produced on said sheet by selectedelectric signals.

2. An electrical coloration recording sheet according to claim 1 whereinsaid electrical coloration material layer is formed of at least one ofmetallic sulfides, metallic oxides, metallic acids, metallic acid salts,other metallic compounds and thermic coloration materials.

3. An electrical coloration recording sheet according to claim 1 whereinsaid electrical coloration material layer is composed of an electricalcoloration material or materials and a binder or binders.

4. An electrical coloration recording sheet according to claim 1 whereinsaid electrical coloration material or materials comprise at least oneof metallic sulfides, metallic oxides, metallic acids, metallic acidsalts, other metallic compounds and thermic coloration materials.

5. An electrical coloration recording sheet according to claim 3 whereinsaid binder or binders comprise at least one of oil-soluble resins,water-soluble resins and other binder materials.

6. An electrical coloration recording sheet according to claim 1 whereinsaid thin electrically conductive material layer comprises at least oneof metals and metallic compounds.

7. An electrical coloration recording sheet according to claim 1 whereinsaid thin electrically conductive material layer is composed of a thinelectrically conductive material layer forming material and at least onebinder.

8. An electrical coloration recording sheet according to claim 7 whereinsaid thin electrically conductive material layer forming materialcomprises of at least one of metals and metallic compounds.

9. An electrical coloration recording sheet according to claim 7 whereinsaid at least one binder material comprises at least one of oil-solubleresins, watersoluble resins and other binder materials.

10. An electrical coloration recording sheet according to claim 1wherein said electrical coloration material layer is formed by vacuumevaporation or application.

11. An electrical coloration recording sheet according to claim 1wherein said thin electrically conductive material layer is formed byvacuum evaporation, spattering or application.

12. An electrical coloration recording sheet comprising an electricalcoloration material layer and an electrically conductive material layer,one flat side of the conductive layer being disposed on the colorationlayer and the other flat side of the conductive layer being exposed,said coloration layer being made of a material which changes colorlocally in response to the application of a selected electrical signalto an adjacent point on the exposed side of the conductive layer, saidcoloration layer remaining continuous after local color changes thereof.

13. A recording sheet as in claim 12 wherein the conductive layer ismade of a material which destructs locally in response to theapplication of said electrical signal to a point thereof.

14. A recording sheet as in claim 12 wherein the col oration layerincludes a material selected from the group consisting of metallicsulfides, metallic oxides, metallic acids, metallic acid salts, andfurther includes a binder selected from the group consisting ofoilsoluble resins and water-soluble resins.

15. A method of forming an image on an electrical coloration recordingsheet comprising an electric coloration material layer and anelectrically conductive material layer having one side disposed on thecoloration layer and the other side exposed, said method comprising thesteps of:

providing a first electrode and a recording electrode;

establishing electrical contact between the exposed side of theconductive layer and the first electrode and a potential differencebetween the first and the recording electrode; and

contacting selected points on the exposed side of the conductive layerwith the recording electrode to cause corresponding points of thecoloration layer to change color without destruction of the points ofthe coloration layer which have changed color.

16. A method as in claim 15 wherein the step of contacting selectedpoints of the conductive layer with the recording electrode includesdestruction of said points of the conductive layer without destructionof the adjacent points of the coloration layer. ll l i

1. AN ELECTRICAL COLORATION RECORDING SHEET COMPRISING AN ELECTRICALCOLORATION MATERIAL LAYER AND A THIN ELECTRICALLY CONDUCTIVE MATERIALLAYER FORMED ON SAID ELECTRICAL COLORATION MATERIAL LAYER, SAIDELECTRICAL COLORATION MATERIAL LAYER MADE OF A MATERIAL WHICH CHANGESCOLOR BUT IS NOT DESTROYED AT A POINT ADJACENT A POINT OF THE THINELECTRICALLY CONDUCTIVE MATERIAL LAYER TO WHICH A SELECTED ELECTRICALSIGNAL IS APPLIED WITH
 2. An electrical coloration recording sheetaccording to claim 1 wherein said electrical coloration material layeriS formed of at least one of metallic sulfides, metallic oxides,metallic acids, metallic acid salts, other metallic compounds andthermic coloration materials.
 3. An electrical coloration recordingsheet according to claim 1 wherein said electrical coloration materiallayer is composed of an electrical coloration material or materials anda binder or binders.
 4. An electrical coloration recording sheetaccording to claim 1 wherein said electrical coloration material ormaterials comprise at least one of metallic sulfides, metallic oxides,metallic acids, metallic acid salts, other metallic compounds andthermic coloration materials.
 5. An electrical coloration recordingsheet according to claim 3 wherein said binder or binders comprise atleast one of oil-soluble resins, water-soluble resins and other bindermaterials.
 6. An electrical coloration recording sheet according toclaim 1 wherein said thin electrically conductive material layercomprises at least one of metals and metallic compounds.
 7. Anelectrical coloration recording sheet according to claim 1 wherein saidthin electrically conductive material layer is composed of a thinelectrically conductive material layer forming material and at least onebinder.
 8. An electrical coloration recording sheet according to claim 7wherein said thin electrically conductive material layer formingmaterial comprises of at least one of metals and metallic compounds. 9.An electrical coloration recording sheet according to claim 7 whereinsaid at least one binder material comprises at least one of oil-solubleresins, water-soluble resins and other binder materials.
 10. Anelectrical coloration recording sheet according to claim 1 wherein saidelectrical coloration material layer is formed by vacuum evaporation orapplication.
 11. An electrical coloration recording sheet according toclaim 1 wherein said thin electrically conductive material layer isformed by vacuum evaporation, spattering or application.
 12. Anelectrical coloration recording sheet comprising an electricalcoloration material layer and an electrically conductive material layer,one flat side of the conductive layer being disposed on the colorationlayer and the other flat side of the conductive layer being exposed,said coloration layer being made of a material which changes colorlocally in response to the application of a selected electrical signalto an adjacent point on the exposed side of the conductive layer, saidcoloration layer remaining continuous after local color changes thereof.13. A recording sheet as in claim 12 wherein the conductive layer ismade of a material which destructs locally in response to theapplication of said electrical signal to a point thereof.
 14. Arecording sheet as in claim 12 wherein the coloration layer includes amaterial selected from the group consisting of metallic sulfides,metallic oxides, metallic acids, metallic acid salts, and furtherincludes a binder selected from the group consisting of oil-solubleresins and water-soluble resins.
 15. A method of forming an image on anelectrical coloration recording sheet comprising an electric colorationmaterial layer and an electrically conductive material layer having oneside disposed on the coloration layer and the other side exposed, saidmethod comprising the steps of: providing a first electrode and arecording electrode; establishing electrical contact between the exposedside of the conductive layer and the first electrode and a potentialdifference between the first and the recording electrode; and contactingselected points on the exposed side of the conductive layer with therecording electrode to cause corresponding points of the colorationlayer to change color without destruction of the points of thecoloration layer which have changed color.
 16. A method as in claim 15wherein the step of contacting selected points of the conductive layerwith the recording electrode includes destruction of said points of Theconductive layer without destruction of the adjacent points of thecoloration layer.